How can I make radial text sweep?
Using shaders (Eevee here but works for Cycles too).


Top part:
Presuming Z is facing the camera, we take X and Y as base for the calculation.
Artan2 gives the angle between -pi and pi for each X and Y position.
Bottom part:
Now from 2 values the current frame and the amount of frames, translate that in order to have a value between 0 and pi.
Then translate it between 0 and -pi (for the left part) and between pi and 0 for the right part.
Transparency:
We compare that to the effective X Y angle and if OK (one or other into the good interval), set alpha to 1 (no transparency).

Another way, that can be considered less maths and/or more flexible is to use a gradient texture with radial mode: